Enzymes are biological catalysts that facilitate biochemical reactions in horses by lowering the activation energy required for these processes. They are involved in various physiological functions, including digestion, metabolism, and cellular repair. Common enzymes in equine biology include amylase, lipase, and lactate dehydrogenase, each playing a specific role in the breakdown of nutrients and energy production. The activity and concentration of these enzymes can vary in response to different physiological and pathological conditions, serving as potential indicators in veterinary diagnostics. This page compiles peer-reviewed research studies and scholarly articles that explore the function, regulation, and clinical implications of enzymes in equine health.
Ronda GJ, Gaastra W, Beintema JJ.The kinetic parameters Km, k+2 and k+2/Km of the pancreatic ribonucleases (EC 3.1.4.22) from cow, giraffe, horse, rat and lesser rorqual have been determined, using 2',3'-cyclic cytidine monophosphate and 2',3'-cuclic uridine monophosphate as substrates. No large differences were found between the activities of the five enzymes. The relative differences between the activities of the five enzymes are mainly due to differences in the rates of hydrolysis and not to differences in the affinities for the substrates.
Kotts C, Jenness R.Kappa-Casein-like proteins were isolated from the milks of cow, goat, reindeer, horse, rat, and rabbit. When treated with rennin, all of the isolated kappa-casein components yielded para-kappa-casein-like bands on gel electrophoresis. The rate of cleavage of these components with rennin was determined by measuring material soluble in trichloroacetic acid (macropeptide). The curves were characteristic of a limited, specific attack by rennin on these proteins. The goat and reindeer kappa-caseins were nearly as bovine kappa-casein, but the cleavage of horse, rat, and rabbit kappa-casein-like comp...
Groman EV, Schultz RM, Engel LL, Orr JC.In the reduction of 17beta-hydroxy-5alpha-androstan-3-one to the 3beta-alcohol, horse liver alcohol dehydrogenase utilizes the 4-pro-R hydrogen of NADH whereas the 3(17)beta-hydroxysteroid dehydrogenase of Pseudomonas testosteroni utulized the 4-pro-S hydrogen. These observations provide an exception to the rule proposed by Alworth and Bentley that with regard to the paired methylene hydrogens at C-4 of NADH and NADPH "the stereospecificity of a particular reaction is fixed and does not vary with the source of the enzyme preparation". It is also apparent that for these two enzymes, the selecti...
Verhaegen M, Sand G.The distribution of protein phosphokinase (EC 2.7.1.37) activities has been established in horse thyroid nuclei. The presence of several enzyme activities has been demonstrated, two of which are clearly distinct. The first one acts on histone as substrate and is activated by cyclic AMP. Physico-chemical properties of this nuclear cyclic AMP-dependent histone kinase and of the cytosol histone kinase are different, demonstrating the absence of a contamination from the cytosol. The second enzyme acts on casein as substrate and is not stimulated by cyclic AMP POR CYCLIC GMP. The findings are consi...
Sogin DC, Plapp BV.Diazonium-1H-tetrazole was tested as a potential active-site-directed reagent for amino acid residues involved in catalysis by alcohol dehydrogenase. In a novel reaction with a protein, diazonium-1H-tetrazole inactivated the enzyme selectively, and almost stoichiometrically, but reacting with the sulfur of a cysteine residue, Cys-174. As a model compound, the tetrazole adduct of free cysteine was prepared. Elementary and spectral analyses of the adduct were consistent with the structure 5-tetrazoleazo-S-cysteine. The adduct absorbs light with a maximun at 316 nm, and is destroyed by irradiatio...
Milne DW, Skarda RT, Gabel AA, Smith LG, Ault K.Effects of training at a regular, fixed, standard exercise load on venous lactic acid, mixed venous and arterial blood gases and pH, and serum muscle enzymes were determined on previously unconditioned, healthy, adult, Standardbred horses. Arterial and mixed venous blood gases, pH, and serum muscle enzymes did not change in a consistent manner during training. Venous lactic acid concentrations did increase significantly with training and may be of value for the biochemical evaluation of fitness in horses.
Anderson MG.The distribution of lactic dehydrogenase, aldolase and creatine kinase in various horse tissues was determined. Using polyacrylamide gel electrophoresis the lactic dehydrogenase and creatine kinase isoenzyme composition of horse serum, taken before and after exercise, was studied. Horse tissue isoenzyme patterns were also obtained. By comparing tissue and serum patterns, skeletal muscle was found to be the tissue of origin of the increase in serum lactic dehydrogenase and creatine kinase observed after exercise.
Anwer MS, Engelking LR, Gronwall R, Klentz RD.Plasma bile acid concentration was determined in normal dogs,sheep, calves and ponies for three days before and six days after liver damage, induced by carbon tetrachloride. In all species, a significant increase in plasma bile acid concentration was associated with a concomitant significant increase in plasma sorbitol dehydrogenase and transferase activity. Plasma bilirubin also significantly increased in all animals except the dogs. Results suggested that plasma bile acid levels could be used to test liver function in domestic animals.
McGuire TC, Pollara B, Moore JJ, Poppie MJ.Foals with combined immunodeficiency had normal levels of purine salvage pathway enzymes, including adenosine deaminase, nucleoside phosphorylase, and xanthine oxidase.
Dubin A, Koj A, Chudzik J.Cytoplasmic granules were isolated from horse blood polymorphonuclear leucocytes by the heparin method and extracted with 0.9% NaCl by repeated freezing. Soluble proteins were separated on a column of Sephadex G-75 followed by chromatography on a column of CM-Sephadex with a NaCl gradient. Gel filtration, density-gradient centrifugation, isoelectric focusing and 0.1% sodium dodecyl sulphate/polyacrylamide-gel electrophoresis at pH 7.0 and at pH 4.5 were used to determine molecular parameters of proteinases. Three enzymes hydrolysing both casein and N-benzyloxycarbonyl-L-alanine nitrophenyl est...
Koj A, Chudzik J, Dubin A.Two proteinases (2A and 2B) purified from the granular fraction of horse blood leucocytes degrade casein (Km values 12.8 and 6mg/ml respectively) with maximum activity at pH 7.4 and in the presence of 2m-urea. Urea-denatured haemoglobin, fibrinogen, albumin and resorcin/fuchsin-stained elastin are digested at a slower rate. The enzymes hydrolyse synthetic substrates of elastase, N-benzyloxycarbonyl-L-alanine 4-nitrophenyl ester (Km 0.114 and 0.178 mM) and N-acetyl-tri-L-alanine methyl ester (Km 5.55 and 0.98 mM), but they do not hydrolyse synthetic substrates of trypsin, chymotrypsin and throm...
Aberle ED, Judge MD, Kirkham WW, Page EH, Crawford BH.Frozen sections of equine musculus semitendinosus were examined for myosin adenosine triphosphatase (ATPase) and reduced nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), using standard histochemical procedures, and the proportions of the various fiber types and average fiber sectional size were determined. With ATPase staining, approximately 70% of the fibers were classified as alpha fibers (ATPase positive), and 30%, as beta fibers (ATPase negative). In addition, 2 populations of alpha fibers could be readily distinguished on the basis of the intensity of the ATPase reaction...
Kurachi K, Schmer G, Hermodson MA, Teller DC, Davie EW.A comparison of the physical-chemical properties of human, bovine, and horse antithrombin III has been made. These three plasma proteins are strong inhibitors of bovine factor Xa and form a 1:1 molar complex with this coagulation enzyme. Human, bovine, and horse antithrombin III are glycoproteins containing hexose, hexosamine, and neuraminic acid. The total carbohydrate was 9, 12, and 16% for human, bovine, and horse antithrombin III, respectively. These proteins have a similar amino acid composition, although some monor variations were noted. Each antithrombin III is composed of a single poly...
Wetz K, Crichton RR.In apoferritin, but not in ferritin, 1.0 +/- 0.1 cysteine residue per subunit can be modified. In ferritin 3.3 +/- 0.3 lysine residues and 7.1 +/- 0.7 carboxyl groups per subunit can be modified, whilst the corresponding values for apoferritin are 4.4 +/- 0.4 lysine residues and 11.0 +/- 0.4 carboxyl groups per subunit. Modification of lysine residues which maleic anhydride and carboxyl groups with glycineamide in apoferritin which has been dissociated and denatured in guanidine hydrochloride leads to the introduction of 9.1 +/- 0.5 maleyl groups per subunit and 22.0 +/- 0.9 glycineamide resid...
Stepanov VM, Lavrenova GI, Rudenskaia GN, Gonchar MV, Lebareva LS.6 forms of pepsin are found in horse gastric juice. Amino acid sequence is determined of N-terminal (most variable) part of polypeptide chain of main pepsin components. Equine pepsines, which have pI 2.1 and 2.3, are found to have identical amino acid sequence at least for 31 amino acid residues. The same sequence is observed in the component with pI 2.6 for 10 first residues. The sequence of equine pepsin with pI 3.2 has 3 substitutions for 33 amino acids, when compared with pepsines having pI 2.1 and 2.3. The forms of equine pepsin studied are more similar than the other isoenzyme pair, huma...
Heyneman RA, Bruyninckx WJ, Vercauteren RE.Two distinct groups of acid phosphatase containing granules were characterized in neutrophils, each group displaying different multiple forms of the enzyme. The heavy granule acid phosphatase showed a lysosomal location. A second lighter group of particles contained a thermolabile, thiol-dependent acid p-nitrophenyl and alpha-naphtylphosphatase, an enzyme clearly different from lysosomal acid phosphatase. Acid phosphatase activity from eosinophil leukocytes appeared to be totally associated with the typical eosinophil granules. On mechanical disruption of these particles, an acid phosphatase w...
Rejnö S.LDH is an intracellular enzyme, which when cells degenerate is released to the extracellular spaces and body fluids. Cells and organs in the mammalian body differ from each other with respect to their LDH isoenzyme patterns. These circumstances have led to the use of LDH isoenzyme determinations in laboratory diagnostic work. In the present investigation total LDH activity and LDH isoenzyme distribution in equine synovial fluid from healthy joints, joints with serous arthritis, osteochondrosis dissecans and arthrosis, were determined. The fluids from the diseased joints differed from normal sy...
Zobel G, Kolb FE.Acid phosphatase of erythrocytes of several species was investigated, with three isozymes having been recorded from swine (three types), three (two types) from horse, four (one type) from dog, two (two types) from cat, two (three types) from duck, and two (one type) from fowl. The Michaelis constant of the enzyme varied between 3.5 and 5 X 10(-4) M for the species involved. The species, however, differed slightly for the optimum pH of the enzyme. The average enzymatic activities were (5.68 +/- 0.42 for dog, 4.46 +/- 1.0 for horse, 3.8 +/- 0.24 for swine, 3.72 for cat, 2.5 +/- 0.62 for duck, an...
Cappugi G, Chellini PC, Nassi P, Ramponi G.A ninhydrin-negative peptide fraction obtained from tryptic digest of carboxymethyl acylphosphatase was isolated by chromatography on a column of PA 28 Beckman resin and analysed for the amino acid composition. Degradation with carboxypeptidase B and A indicated that the sequence of this peptide was: X-Thr-Ala-Arg. The amino-terminal residue was identified as N-acetylserine by high voltage electrophoresis. It is therefore suggested that the sequence of the NH2-terminal portion of CM-acylphosphatase is N-acetyl-Ser-Thr-Ala-Arg. Digestion with carboxypeptidase A and B indicated also that the COO...
Sytkowski AJ, Vallee BL.The catalytic and non-catalytic Zn atom pairs of horse liver alcohol dehydrogenase (LADH) have been replaced sequentially either by 65Zn, Co or 65Zn and Co. The Co derivatives exhibit characteristic spectra. When Co replaces the Zn atoms which exchange secondly, enzymatic activity is altered, and both imidazole and 1,10-phenanthroline (OP) significantly modify the spectrum of the catalytic Co atoms. Further, due to the removal of cobalt, the instantaneous and reversible OP inhibition of the native enzyme becomes time-dependent and irreversible. Jointly, these data identify the pair of metal at...
Schotman AJ, Wensing T, Ockels J, de Bruyne JJ, Hendriks HJ.To examine the suitability and reliability in field use of the "Merckognost Harnstoff" method in estimating the concentration of urea in the blood of horses, cattle, goats and dogs, the levels determined by this procedure were compared with those determined by an enzymatic (urease) photometric method widely used in laboratories. It was concluded from the results obtained that estimation using the "Merckognost Harnstoff" is sufficiently reliable for the rapid assay of urea in the blood under field conditions.
Roberts MC.Lactase and cellobiase were detectable in the fetal intestine by the 3rd month of gestation, and although there was little change by the 9th month, maximal levels were reached at birth and steadily declined after 4 months. Conversely maltase, sucrase and trehalase were barely discernible in the fetus, maltase being present at low levels at birth, but all increased during the suckling period to attain adult levels by 7 months of age. Alkaline phosphatase activity matured earlier than did disaccharidase activity. Mucosal enzymes other than alkaline phosphatase were virtually absent from meconium...
Deutsch HF, Bray RP.A study of the erythrocyte carbonic anhydrases of 219 American ponies and 76 riding horses has revealed the presence of five variants of the low-activity CA B isozyme and two variants of the high-activity CA C isozyme. The previously undetected variant of CA C was found only in the pony population and had an allele frequency of 8.9%. A family study of animals possessing the CA B variant A2 showed an unexpected high frequency of inheritance.
Hay MF, Allen WR, Lewis IM.Graafian follicles of various sizes obtained from mares at different stages of the oestrous cycle were examined histologically and histochemically for delta5-3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity and related enzymes. The 3beta-HSD activity was not found in the theca interna of any follicles but was present in the membrana granulosa of well-vascularized large follicles in the late luteal phase of the cycle and at oestrus. These findings indicate that pregnenolone cannot be converted into progesterone in the theca interna. It is suggested that this conversion occurs in the memb...
Flood PF, Marrable AW.The distribution of several hydroxysteroid dehydrogenases (HSD) was examined in a variety of equine placental and fetal tissues. The main points of interest were: (a) the lack of dehydrogenase activity in the gonad, (b) the appearance of a variety of HSDs in the trophoblast as early as 13 days of gestation, (c) the histochemical similarity between the cells of the trophoblast and the endometrial cup, and (d) the restriction of the strong endometrial 17beta-HSD reaction to those parts of the uterine epithelium directly apposed to the trophoblast.
Sander J, Terhardt M, Janzen N.In horses, congenital defects of energy production from long-chain fatty acids have not been described so far. In contrast, inhibition of fatty acid degradation caused by the toxins hypoglycin A and methylenecyclopropylglycine from various maple species are observed frequently. These non-proteinogenic aminoacids are passed on placentally to fetuses or with collostrum or milk to newborn foals. Nevertheless, newborn foals become very rarely symptomatic. Vertical transmission apparently is not sufficient to induce clinical disease without a particular genetic constellation being present. One of t...
Dumasia MC.The in vivo biotransformation of metoprolol tartrate in the thoroughbred racehorse was studied after administration of a single oral dose. Metoprolol and its basic and bifunctional phase I metabolites were isolated from urine and plasma using mixed mode solid phase extraction (SPE) cartridges. The isolates were derivatised as trimethylsilyl ethers and analysed by capillary column gas chromatography--positive ion electron ionisation and ammonia chemical ionisation mass spectrometry. Metabolism was primarily confined to the oxidative transformations of the p-(2-methoxy)ethyl substituent. Metopro...
Paik WK, Farooqui J, Gupta A, Smith HT, Millett F.The present observations are the continuation of our earlier study on the physicochemical mechanism of protein-lysine methylation. In this paper the electrophoretic behaviour (pI values) of two chemically modified horse heart cytochromes c at lysine-72 with trifluoromethylphenylcarbamoyl (neutral group) or carboxydinitrophenyl (acidic group) is compared with the enzymatically methylated cytochrome c. The results indicate that although both chemically modified cytochromes c have lower pI values than the unmodified cytochrome c, the enzymatic methylation appears to be much more efficient in lowe...
Foreman-Hesterberg CR, Foreman JH.Muscle damage can result in leakage of intracellular enzymes such as creatine kinase (CK) and aspartate transaminase (AST) into plasma. There are no controlled documentations of the effects of intramuscular antibiotic drug administration on plasma CK and AST activities in horses. The objective of this experiment was to test the hypothesis that 5 days of intramuscular procaine penicillin G injection in normal horses would result in increased plasma activities of CK and AST. Nine healthy adult horses were sampled for 7 days preceding, 5 days during, and 32 days following procaine penicillin G (2...
Kósa CA, Nagy K, Szenci O, Baska-Vincze B, Andrásofszky E, Szép R, Keresztesi Á, Mircean M, Taulescu M, Kutasi O.A severe form of recurrent exertional rhabdomyolysis occurs enzootically in a well-defined region of Transylvania, Harghita county. At the highest lying two settlements (more than 800 m above sea level), the prevalence of equine rhabdomyolysis is between 17 and 23%, while in the neighbouring villages in the valley it is less than 2%. The objective of our study was to clarify the role of selenium and vitamin E in the high prevalence of rhabdomyolysis in that region. Soil and hay samples were collected from each area to evaluate mineral content. Ten horses from the non-affected and 20 horses fro...
Salloum RM, Duckworth D, Madison JB, Souba WW.The sodium-dependent transporter system responsible for L-glutamine uptake by brush border membrane vesicles prepared from equine jejunum was characterized. Vesicle purity was ascertained by a 14- to 17-fold increase in activity of the brush border enzyme markers. Glutamine uptake was found to occur into an osmotically active space with negligible membrane binding. The sodium-dependent velocity represented approximately 80% of total uptake and demonstrated overshoots. Kinetic studies of sodium-dependent glutamine transport at concentrations between 5 microM and 5 mM revealed a single saturable...
George JW, Duncan JR, Mahaffey EA.Pyrimidine 5'nucleotidase (P5N) activities of erythrocytes for Mongolian gerbils, cats, dogs, sheep, horses, and calves were measured, using a radiometric technique with [14C]cytidine monophosphate as the substrate. Erythrocytes of gerbils had the highest activity [1,177.1 +/- 133.6 mU/g of hemoglobin (Hb)]. Feline erythrocytes had 327.4 +/- 204.4 mU/g of Hb. Canine erythrocytes had 148.0 +/- 19.8 mU/g of Hb. Ovine erythrocytes (44.3 +/- 20.9 mU/g of Hb), equine erythrocytes (30.0 +/- 15.9 mU/g of Hb), and bovine erythrocytes (14.1 +/- 6.9) had relatively low P5N activity. The P5N activity was...
van den Hoven P, Meijer AE, Breukink HJ, Wensing T.Muscle biopsies from six horses with clinical histories of muscle atrophy, muscle tremors, myopathic symptoms, unsteadiness of pelvic limbs and progressive ataxia were examined. Muscle biopsies were studied with enzyme histochemical techniques to evaluate the diagnostic values of these methods in cases suspected of suffering from neuromuscular disorders. Hypertrophy, atrophy, fibre splitting, waxy degeneration, phagocytosis and necrosis were seen in haematoxylin eosin stained sections of the different cases. Fibre type predominance and fibre type grouping were seen in the calcium ion stimulate...
Weston MC, Collins ME, Cunningham FM.Inappropriately activated eosinophils can contribute to disease pathogenesis and intracellular signalling pathways that regulate functional responses may represent a therapeutic target. Little is known about intracellular signalling in equine eosinophils and this study examined the role of phospholipase C (PLC) and a range of protein kinases on responses to histamine and CCL11. Histamine (10(-4) M) or CCL11 (5.6 x 10(-9) M)-induced actin polymerization, migration and superoxide production by eosinophils from healthy horses were compared in the presence and absence of selective kinase inhibitor...
Minelli A, Moroni M, Trinari D, Mezzasoma I.Ectoenzymic activities capable of hydrolyzing ATP sequentially to adenosine are present on equine epidydimal spermatozoa membranes. Kinetic parameters for ATPase, ADPase and 5'-nucleotidase were obtained by analysis of progress reactions curve when ATP, ADP and AMP were supplied as initial substrates. These values are not different from those found when the substrates were supplied from the preceding reactions. Feed-forward inhibition on 5'-nucleotidase by ATP/ADP was taken into account to fit simulated data to the experimental results. None of the substrates supplied by the preceding reaction...
Braun JP, Tainturier D, Bézille P, Raviart I, Rico AG.In goat and mare colostrum, gamma-glutamyltransferase (GGT) activity is relatively low (mean values are, respectively, 900 and 350 U/l). In the serum of newborns before suckling, GGT is also low (less than or equal to 28 U/l in goats and less than or equal to U/l in foals); then in goats GGT is much increased on the 1st day (mean = 127 U/l), and it decreases during the following days. In foals, serum GGT slowly but regularly increases for the first 5 days, then decreases. Such differences can be attributed to intestinal protein absorption capabilities which are selective in newborn foals and u...
Asquith RL, Edds GT, Aller WW, Bortell R.Twelve clinically normal Shetland ponies were allocated to one of four treatment groups. Aflatoxin B1 was administered at the dosage level of 2 mg/kg of body weight to group A, 1 mg/kg to group B, and 0.5 mg/kg to group C; a placebo was given to group D (controls). Plasma samples were assayed at 4-hour intervals for iditol dehydrogenase (ID) (sorbitol dehydrogenase) concentrations as an indicator of hepatic damage. One of the ponies in group A died 68 hours after dosing; another pony in group A died 76 hours after dosing. All other animals survived the experiment. The means of peak ID values w...
Knych HK, Finno CJ, Baden R, Arthur RM, McKemie DS.The in vivo metabolism and pharmacokinetics of flunixin meglumine and phenylbutazone have been extensively characterized; however, there are no published reports describing the in vitro metabolism, specifically the enzymes responsible for the biotransformation of these compounds in horses. Due to their widespread use and, therefore, increased potential for drug-drug interactions and widespread differences in drug disposition, this study aims to build on the limited current knowledge regarding P450-mediated metabolism in horses. Drugs were incubated with equine liver microsomes and a panel of r...
Dyrda K, Orzołek A, Ner-Kluza J, Wysocki P.Phosphorylation and dephosphorylation of proteins are considered to be the most important processes in sperm maturation during epididymal transit. The main aim of this study was to isolate and identify phosphoproteins from the epididymal milieu obtained from reproductively mature stallions during and out of the breeding season. With the use of 1D-PAGE and nanoLC-MS/MS, we identified phosphoproteins that fulfil various functions: regulatory, transport, motility, ubiquitination, chaperone, antioxidant, apoptotic and enzymatic. Moreover, we characterized tyrosine, serine and threonine phosphoryla...
Kumar S, Sharma D, Kumar R.The effect of denaturants on the structural fluctuation of M80-containing Ω-loop of ferrocytochrome c was determined by measuring the rate coefficient of CO-association with ferrocytochrome c under varying concentrations of urea and alkylureas (methylurea (MU), N,N'-dimethylurea (DMU), ethylurea (EU), tetramethylurea (TMU)) at pH7.0, 25°C. As denaturant concentration is increased within the subdenaturing limit, the CO-association reaction is decelerated indicating that subdenaturing concentrations of denaturant reduce the structural fluctuation of the Ω-loop. Structural fluctuation of the ...
Maisi P, Paananen M, Koivunen AL.Seventeen trotters, eight healthy and nine with a mild respiratory disease, underwent a submaximal treadmill exercise. Heart rate, breathing frequency, intrapleural pressure difference (IP difference) as well as haematocrit and concentration of lactic acid in blood were monitored before exercise, during exercise and during recovery. The activities of beta-glucuronidase and plasmin, total proteolytic activity and trypsin inhibitory capacity were measured from the tracheal fluid before and after exercise. IP difference significantly increased during exercise and returned to normal values within ...
Coyne CP, Smith JE, DeBowes RM.Several pharmaceutical compounds were evaluated for their ability to selectively inhibit activated coagulation factor-XIII-like enzyme activity (eg, XIIIa*) in pooled equine plasma. Presence of coagulation factor-XIIIa*-like enzyme activity in plasma was established by assay procedures involving incorporation of the fluorescent amine compound, monodansylcadaverine, into purified casein, which served as a protein substrate. Pharmaceuticals inhibitory to coagulation factor-XIIIa*-like enzyme activity were recognized by plasma gel formation of high spectrophotometric transmittance (transparency),...
Batt RM, Burgess D, Edwards GB, van de Waal S, Sørensen SH, Hart CA.To examine the postnatal development of equine small intestine, biopsy specimens of jejunal mucosa from 8 ponies, between 6 and 28 weeks old, were subjected to analytical subcellular fractionation and assay of organelle marker enzymes. Fractionation revealed a reduction in the particulate brush border component of beta-galactosidase (lactase) activity between 6 and 28 weeks, and a corresponding increase in soluble activity, although the reduction in mean specific activity was not significant. There also was a decrease in the proportion of brush border to soluble aminopeptidase N activity, a re...
Yagisawa S.One mole of horse hemoglobin tetramer reacts with 2 moles of 2-chloromercuri-4-nitrophenol (MNP) at beta 93 cysteine. The difference spectra between NMP-bound hemoglobin and hemoglobin, measured with the aid of ascorbic acid and ascorate oxidase [EC 1.10.3.3] as deoxygenation reagents, indicate that the pK of the phenolic hydroxyl group of MNP increases by 0.6 to 0.8 pH unit on deoxygenation of the hemoglobin. The Hill constant of the modified hemoglobin changes with pH. It decreases from about 2.4 at pH 6.8 to about 1.0 at pH 9.0 This effect of the reagent is interpreted as inherent to the re...
Yoshimura T, Sogabe T, Aki K.Electron transfer between horse heart and Candida krusei cytochromes c in the free and phosvitin-bound states was examined by difference spectrum and stopped-flow methods. The difference spectra in the wavelength range of 540-560 nm demonstrated that electrons are exchangeable between the cytochromes c of the two species. The equilibrium constants of the electron transfer reaction for the free and phosvitin-bound forms, estimated from these difference spectra, were close to unity at 20 degrees C in 20 mM Tris-HCl buffer (pH 7.4). The electron transfer rate for free cytochrome c was (2-3).10(4)...
Campbell-Thompson M.Equine oxyntic mucosal cells were obtained by sequential exposure to pronase and collagenase. Acid production by parietal cells was assessed by uptake of [14C]aminopyrine (AP), a weak base that accumulates in intracellular acidic spaces. Incubation for various times revealed a maximal AP uptake at 10 minutes for histamine and carbachol. Similar secretagogue responses were observed for parietal cells from the mucosal cell preparation or after enrichment by elutriation. Histamine and isobutyl-methylxanthine (IBMX) stimulated AP uptake with a dose-dependent response and maximal effective concentr...
Pellegrini A, Zweifel HR, von Fellenberg R.Several publications have described in the past properties of partly purified horse alpha 2-macroglobulin (alpha 2M) which are strikingly different from the human alpha 2M. Horse alpha 2M was therefore isolated to purity by classical procedures, i.e. affinity chromatography, ion exchange chromatography and gel filtration, and its properties are compared with those of its human counterpart. The molecular weight of the native protein and its subunits, the isoelectrofocusing pattern and the change in electrophoretic mobility caused by interaction with protease were similar to those of human alpha...
Holland RA.Using a double beam stopped-flow apparatus, measurements were made of the velocity constant of the reaction CO + Hb --> COHb in solution and in the red cells of human beings, rabbits, horses, and goats. The solution constant (l') at 37 degrees C for human beings was 362 mM(-1) sec.(-1); in other species l' was somewhat lower. Two rabbits, despite having apparently identical hemoglobins had significantly different values for l'. The energy of activation (E) of l' was between 8 and 11 kcal/mole in all cases. The cell reaction constant (l'(c)) at 37 degrees was between 61 and 73 mM(-1) sec.(-1...
Greenaway EC, Cunningham FM, Goode NT.Phorbol esters, which activate protein kinase C (PKC), stimulate equine eosinophil superoxide production and adherence. After showing that superoxide production could be inhibited by the nonselective PKC inhibitors, staurosporine and bisindolymaleimide I, the PKC isotypes in equine eosinophils were characterized, because evidence suggests that individual isotypes may play distinct roles in regulating eosinophil function. Western blots demonstrated that equine eosinophils expressed PKC alpha, beta, delta, epsilon, iota, and zeta. However, unlike the equine neutrophil, the majority of the PKC wa...
Rickards KJ, Page CP, Hamblin AS, Goode NT, Cunningham FM.Lymphocytes play an important role in allergic inflammation and have been implicated in the pathogenesis of equine allergic skin and respiratory disease. Targeting intracellular signalling pathways in human lymphocytes has demonstrated a role for both phosphodiesterase and protein kinase C in cell activation. The aim of this study was to measure total cyclic nucleotide hydrolysing phosphodiesterase activity and to identify the phosphodiesterase and protein kinase C isoenzymes present in equine lymphocytes. The functional significance of these isoenzymes was then investigated by examining their...
Sommardahl CS, Andrews FM, Saxton AM, Geiser DR, Maykuth PL.Packed cell volume and plasma total protein (TP), serum albumin (Alb) and globulin (Glb), and plasma ionized calcium (PCa) concentrations, blood viscosity (BV), and plasma viscosity (PV) were measured in 42 horses at rest and after the cross country jumping phase of a horse trial competition. The BV and PV were determined at 6 shear rates (230, 115, 46, 23, 11.5, 5.75 s-1), using a digital rotational cone and plate microviscometer. A paired t-test was used to determine differences between PCV, TP, Alb, Glb and PCa values at rest and after exercise. The PCV, TP, Alb, and Glb values increased (P...
Smith P, Stubley D, Blackmore DJ.Methods were developed for the measurement of superoxide dismutase (SOD), diamine oxidase (DAO) and caeruloplasmin oxidase in the blood of thoroughbred horses. These enzymes were measured in 178 normal thoroughbreds stabled throughout the United Kingdom. The relationships between the activities of SOD, DAO and caeruloplasmin oxidase and the blood concentrations of their associated trace metals (copper, zinc and manganese) were studied in 52 of the thoroughbreds. Trace metals were measured by electrothermal atomic absorption spectrophotometry. No relationships were found between the activities ...
Kampl B, Dominis-Kramaric M, Bacar-Huskic L.The activities of leukocyte alkaline phosphatase (l-AP) and serum gamma-glutamil transferase (gamma-GT), and total leukocyte counts were determined in horses submitted to the production of hyper immune sera against tetanus (Clostridium tetani). The purpose of this work was to investigate the prospective changes of mentioned parameters in horses under the described circumstances. In addition, the suitability of these parameters in assessing the health condition of the same horses had to be evaluated. The average total leukocyte count increased in one month from the values considered as physiolo...
Kaneko JJ, Rudolph WG, Wilson DW, Carlson GP.Serum bile acids were fractionated by high-performance liquid chromatography (HPLC) in 13 control and 8 cases of liver disease in horses. The severity and type of liver injury was determined by histopathological examination of biopsy and/or necropsy specimens. The total serum bile acids (tSBA) were determined in these horses by an enzymatic method (SBA-EA) and by summation of the bile acids (SBA-LC) as fractionated by the HPLC. The SBA-LC were generally higher than the SBA-EA in both the controls and liver disease and they did not parallel each other. The primary bile acids, total cholates and...
Wong JK, Tang FP, Wan TS.The study of the metabolism of drugs, in particular steroids, by both in vitro and in vivo methods has been carried out in the authors' laboratory for many years. For in vitro metabolic studies, the microsomal fraction isolated from horse liver is often used. However, the process of isolating liver microsomes is cumbersome and tedious. In addition, centrifugation at high speeds (over 100 000 g) may lead to loss of enzymes involved in phase I metabolism, which may account for the difference often observed between in vivo and in vitro results. We have therefore investigated the feasibility of us...
